'Grease' actor Jeff Conaway, whose shambolic life was made painfully public during a 2008 stint on 'Celebrity Rehab,' has slipped into a coma and is in critical condition following a drug overdose last week. The former 'Taxi' star's manager, Phil Brock, says the 60 year old was found unconscious on May 11 after possibly OD'ing on pain pills.

Brock would not disclose what hospital Conaway is admitted to, only that it is located in Encino, Calif. The actor's recovery is uncertain.

"He is in a coma and unresponsive at this time," Brock told E! Online. "He turned his head two days ago, but nothing since."